[v9,00/10] fsdax: introduce fs query to support reflink

Message

Shiyang Ruan Dec. 26, 2021, 2:34 p.m. UTC

This patchset is aimed to support shared pages tracking for fsdax.

Changes from V8 Resend:
  - Fix usage of dax write/read lock
  - Remove fsdax/xfs register/unregister wrappers
  - Move unrelated fixes into separate patchset
  - Fix code style

Changes from V8:
  - Rebased to "decouple DAX from block devices v2"
  - Patch8(implementation in XFS): Separate dax part to Patch7
  - Patch9: add FS_DAX_MAPPING_COW flag to distinguish CoW with normal

This patchset moves owner tracking from dax_assocaite_entry() to pmem
device driver, by introducing an interface ->memory_failure() for struct
pagemap.  This interface is called by memory_failure() in mm, and
implemented by pmem device.

Then call holder operations to find the filesystem which the corrupted
data located in, and call filesystem handler to track files or metadata
associated with this page.

Finally we are able to try to fix the corrupted data in filesystem and
do other necessary processing, such as killing processes who are using
the files affected.

The call trace is like this:
memory_failure()
|* fsdax case
|------------
|pgmap->ops->memory_failure()      => pmem_pgmap_memory_failure()
| dax_holder_notify_failure()      =>
|  dax_device->holder_ops->notify_failure() =>
|                                     - xfs_dax_notify_failure()
|  |* xfs_dax_notify_failure()
|  |--------------------------
|  |   xfs_rmap_query_range()
|  |    xfs_dax_failure_fn()
|  |    * corrupted on metadata
|  |       try to recover data, call xfs_force_shutdown()
|  |    * corrupted on file data
|  |       try to recover data, call mf_dax_kill_procs()
|* normal case
|-------------
|mf_generic_kill_procs()

==
Shiyang Ruan (10):
  dax: Use percpu rwsem for dax_{read,write}_lock()
  dax: Introduce holder for dax_device
  mm: factor helpers for memory_failure_dev_pagemap
  pagemap,pmem: Introduce ->memory_failure()
  fsdax: fix function description
  fsdax: Introduce dax_lock_mapping_entry()
  mm: move pgoff_address() to vma_pgoff_address()
  mm: Introduce mf_dax_kill_procs() for fsdax case
  xfs: Implement ->notify_failure() for XFS
  fsdax: set a CoW flag when associate reflink mappings

 drivers/dax/device.c        |  11 +-
 drivers/dax/super.c         | 104 ++++++++++++++--
 drivers/md/dm-writecache.c  |   7 +-
 drivers/nvdimm/pmem.c       |  16 +++
 fs/dax.c                    | 174 +++++++++++++++++++++------
 fs/fuse/dax.c               |   6 +-
 fs/xfs/Makefile             |   1 +
 fs/xfs/xfs_buf.c            |  15 +++
 fs/xfs/xfs_fsops.c          |   3 +
 fs/xfs/xfs_mount.h          |   1 +
 fs/xfs/xfs_notify_failure.c | 189 +++++++++++++++++++++++++++++
 fs/xfs/xfs_notify_failure.h |  10 ++
 include/linux/dax.h         |  63 +++++++++-
 include/linux/memremap.h    |   9 ++
 include/linux/mm.h          |  15 +++
 mm/memory-failure.c         | 232 +++++++++++++++++++++++++-----------
 16 files changed, 719 insertions(+), 137 deletions(-)
 create mode 100644 fs/xfs/xfs_notify_failure.c
 create mode 100644 fs/xfs/xfs_notify_failure.h